Semiconductor element technology, as a core of a display device, has made great progress along with the rapid development of display technology. For an existing display device, an Organic Light Emitting Diode (OLED), as a current-mode light-emitting element, is widely applied to the field of high performance display due to its features such as self-illumination, rapid response, a wide viewing angle as well as that it can be manufactured on a flexible substrate. There are two kinds of OLED depending on the driving modes, they are Passive Matrix Driving OLED (PMOLED) and Active Matrix Driving OLED (AMOLED). An AMOLED display, as a next-generation, new-type flat panel display, is expected to replace a Liquid Crystal Display (LCD) due to its advantages such as low production cost, high response speed, power economy, a wide operating temperature range and DC drive that makes it applicable for a portable device.
In an existing AMOLED display panel, each OLED includes a plurality of Thin Film Transistor (TFTs) switching circuits. Due to limitations in the production processes and production levels, usually the TFT switching circuits formed on a large-area glass substrate show non-uniformity in some electrical parameters such as a threshold voltage and mobility, such that the current flowing through the AMOLED not only varies along with the change of a stress of an on-state voltage caused by a long-time on-state of the TFT, but also varies along with the threshold voltage drift of the TFT. As a result, the brightness uniformity and brightness constancy of the display is affected. Furthermore, the AMOLED, during the operation, is in a bias state for a long period of time, so the degrading of the display device is accelerated, and as a result the service life of the display device is shortened.